1. Field
Example embodiments relate to methods of detecting errors (or faults) of reticles used in photolithography performed during manufacturing of a semiconductor device. Also, example embodiments relate to methods of directly detecting errors of reticles from an exposure unit.
2. Description of Related Art
In general, various processes may be required to manufacture semiconductor devices. The processes may be classified into thin film deposition, photolithography, etching, and/or ion implantation. Thin film deposition may be for depositing a thin film on a wafer (a semiconductor substrate), for example, a silicon wafer; photolithography and/or etching may be for forming the deposited thin film in a pattern that may or may not be predetermined; and/or ion implantation may be for implanting impurities into the wafer.
In particular, photolithography may be a process for forming a photoresist film on a thin film deposited on a wafer, and/or exposing and/or developing the photoresist film using an exposure unit and/or a reticle (mask) installed in the exposure unit, thereby forming a photoresist pattern. The exposure unit may include a stepper and/or a scanner. The reticle may refer to a transparent substrate, including a mask pattern (reticle pattern) having a critical dimension (CD) formed thereon, and/or may be an optical element that allows light emitted from the exposure unit to selectively penetrate the photoresist film. The mask pattern having a CD may be transcribed onto the photoresist film by light transmitted through the reticle. The photoresist pattern, having a CD that may be the same as that of the mask pattern, may be formed by developing the photoresist film.
In general photolithography, the CD of the mask pattern formed on the reticle may be different from the CD of the photoresist pattern formed on the wafer. It may be deemed that such a difference in the CD between the mask pattern and the photoresist pattern exists due to an exposure unit error generated in the exposure unit and/or a reticle error generated in the reticle.
However, in a photolithography process for exposing and developing the photoresist film formed on the wafer, it may be hard to clearly classify the error of the exposure unit and/or the reticle error. In other words, it may be hard to clearly detect which elements affect the generation of the reticle error on the wafer. In general, the reticle error may be detected or examined using a reticle inspection tool, but the reticle error generated on the wafer may not be clearly specified. In addition, when the reticle error is detected or examined using the reticle inspection tool, a long time may be needed for the detection or examination.